Time and frequency transfer through a network of GNSS receivers located in timing laboratories

Abstract

Today, an increasing number of users need high- quality GNSS products, such as precise satellite orbit and clock estimations and predictions, accurate receiver coordinates or tropospheric delays for their applications (e.g., precise point positioning, GNSS augmentation services, weather services, etc). In recent years, many national timing laboratories have collocated geodetic Global Positioning System receivers together with their traditional GPS/GLONASS Common View receivers and Two Way Satellite Time and Frequency Transfer equipments. Time and frequency transfer using GPS code and carrier-phase, is an important research activity for many institutions involved in time applications. This was recognized when the International GNSS Service (IGS) and Bureau International des Poids et Mesures (BIPM), formed a joint pilot study to analyze the IGS Analysis Centers clock solutions and recommend new means of combining them. Many of geodetic GNSS receivers hosted in national timing laboratories, operate continuously within the International GNSS Service (IGS) and their data are regularly processed by IGS Analysis Centers. Whereas participating stations must agree to adhere to certain strict standards and conventions which ensure the quality of the IGS Network, a number of products and tools have been developed in order to allow time and frequency transfer without taking part to the IGS, magicGNSS is a suite of GNSS SW products developed by GMV in Madrid, that allows the users to perform a wide range of calculations and analyses related to GNSS, from the evaluation of performances at user level to the computation of precise GNSS orbits and clocks, including the calculation of precise receiver coordinates. In the present work, time and frequency transfer capabilities of this tool are evaluated, with the aim of exploring a possible network solution for geodetic GNSS receivers located in National Timing Laboratories not necessarily taking part to the IGS and aiming at comparing their time scales at the maximum level of precision.